Endodontics Working Length

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2006 J.Bringas, DMD, DDS, MS

Working Length Determination

Presented by:

Josef Ma. Karlos S. Bringas, D.M.D., D.D.S., M.S.

Department of Endodontics
http://www.udmercy.edu/http://www.udmercy.edu/


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Radiographic Length

The length of the tooth as it appears

on the radiograph.


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Estimated Working Length

Radiographic length minus 1mm.


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Final Working Length

is determined to be -1 mm from the

anatomical apex as measured from

the working length (WL) radiograph.

THIS IS THE LENGTH TO

WHICH THE CANAL WILL BE

CLEANED & SHAPED ANDOBTURATED.


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Select a Reference Point


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Take a Preoperative Radiograph


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Preoperative Radiograph

Measure the

radiographic length.

Reference pt.

Apex


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Measure the radiographic length

Ex. 22mm


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Compute for Estimated Length

Estimated Lengthis

radiographic length

minus 1mm.

Ex. 22mm - 1mm = 21mm


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Treatment Record


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Treatment Record

Incisal edge 21 mm


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Set #15 file to Estimated Length

Insert the file into the canal to stopper

length and take a radiograph at this time.


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Working Length Radiograph

The best casescenario is that thereis no radiographicdistortion with the

preoperativeradiograph.

The working lengthradiograph should

show that the fileends 1mm short ofthe apex.


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File appears to

end 1mm short

of the apex.

No need toadjust the final

working length.


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In this case, estimated

working length

is equaltothe final

working length. EWL = FWL

Record FWL


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Treatment Record

Incisal edge 21 mm 21 mm


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Sometimes, theradiograph showsthat the file extendsmore apical than theideal.

This means that theEWL is long.

Deductthisdiscrepancy from

your EWL to arriveat the Final WorkingLength.


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Example:

EWL=21mm

Since radiographshows that file is 1mm

long then

1mm


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Example:

EWL1mm = FWL

21mm1mm = 20mm

1mm


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Example:

EWL1mm = FWL

21mm1mm = 20mm

1mm


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Treatment Record

Incisal edge 21 mm 20 mm


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Sometimes, theradiograph showsthat the file does notreach the ideallength.

This means that theEWL is short.

Addthisdiscrepancy to your

EWL to arrive at theFinal WorkingLength.


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Example:

EWL+0.5 mm=FWL

21mm+0.5mm=21.5mm

0.5mm


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Treatment Record

Incisal edge 21 mm 21.5 mm


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If the radiograph shows that the

discrepancy is more than 2mm, then a

new radiograph should be taken after

computing for the working length.


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Unacceptable discrepancy

Endodontics Working Length

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